Portable radio device movable with a speaker-microphone, and a wireless communication method

ABSTRACT

During standby (waiting time), a microcomputer of a portable radio device monitors positional information based on the RSSI level (received signal strength) of receiving standby signals and GPS data. Then, when it is detected, based on the positional information based on the RSSI level (received signal strength) and the GPS data, that the radio device has entered an area outside a radio communication enabled area, namely an out-of-service area, the microcomputer carries out a power save processing.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2014-59309, filed on Mar. 21,2014, the entire contents of which are incorporated herein by reference.

BACKGROUND

1. Field

The present invention relates to a portable radio device and a radiocommunication method and, more particularly, to a portable radio device,which is communicatable via Bluetooth (Bluetooth: registered trademark)between battery-powered speaker-microphones and which is movable withthe speaker-microphone, and the radio communication method therefor.

2. Description of the Related Art

There are available portable radio devices, which are communicatable,via Bluetooth, between battery-powered speaker-microphones (or headsets)that are movable with their speaker-microphones. Among those portableradio devices, a portable radio device, for communicating with a partnerstation using a simplex (half duplex) scheme, transmits a transmittingvoice of a user collected by a speaker-microphone, via Bluetoothcommunications, to the portable radio device and further wirelesslytransmits the transmitting voice from the portable radio device to apartner station through a relay station. At this time, the partnerstation is in a receiving state. When, on the other hand, the partnerstation is in a transmission state, the portable radio device isswitched to a receiving state. Then the transmitting voice wirelesslytransmitted from the partner station is received by the portable radiodevice via the relay station, and the transmitting voice received isfurther transmitted to the speaker-microphone via Bluetoothcommunications. As a result, the transmitting voice is received andproduced as voice sound by the speaker-microphone.

In a portable radio device with a speaker-microphone for business orcommercial use among those equipped with the speaker-microphones usingthe simplex (half duplex) scheme, the user starts a call immediatelyafter a push-to-talk (PTT) switch at the outset of a communication isoperated. Thus, a transmission state starts upon activation of the PTTswitch, and an attack time at which the modulation is actually feasibleis defined accordingly. In the receiving, too, a received voice issuddenly outputted unlike a mobile phone where the received voice isoutputted after a telephone calling operation has responded to anincoming call.

Accordingly, for such a portable radio device equipped with thespeaker-microphone for business use, it is preferable that the voicecommunication is constantly enabled within a call possible zone (e.g.,wireless service area or radio communication enabled area), and theheadset profile (HSP) is used as the Bluetooth profile. As a result, thebattery saving of the speaker-microphone is not carried out.

Also, in the portable radio device with the speaker-microphone forbusiness use, the battery saving of the battery-poweredspeaker-microphone is not done although conventionally the transmissionand the receiving in the radio communication do not need to becontrolled in an area outside the call possible zone (an out-of-servicearea). In this case, the electric power of the battery-poweredspeaker-microphone is constantly consumed in the conventional portableradio device with the speaker-microphone for business use, thus causinga problem of reduced battery life.

In the light of this, conceivable for the purpose of reducing the powerconsumed by the speaker-microphone is a method where the power saving iscarried out, except during a call, using the hands-free profile (HFP) ofthe Bluetooth profile.

Also conceivable for the purpose of reducing the power consumed by thespeaker-microphone is employing a known method, as cited in Reference(1) of the following Related Art List, for reducing the power consumedby a mobile terminal device. A conventional method, cited in Reference(1) of the following Related Art List, for reducing the power consumedby a mobile terminal device, is as follows. That is, when the device isnot in used for a predetermined duration of time with a function beingturned on, it is determined that the function be turned off and, at thattime, the position and the power use state or condition of the mobileterminal device are registered. Then, in the thus registered position,control is performed such that the mobile terminal device is in theregistered power use state. As a result, the functions not in use areturned off and therefore the wasted power consumption is reduced. Theposition of the mobile terminal device is acquired by a known methodusing a global positioning system (GPS).

RELATED ART LIST

(1) Japanese Unexamined Patent Application Publication No. 2012-249102.

However, in the method where the power saving of the speaker-microphoneis carried out using the hands-free profile (HFP) of the Bluetoothprofile, HFP is one prepared to suit a mobile phone (e.g., smartphone).Thus, the power saving function gets active as soon as the telephonecalling operation starts. This causes a problem where the voice in acall may be clipped off at the beginning of the voice even though theBluetooth communication is activated immediately after the activation ofthe PTT switch.

On the other hand, when the conventional method, cited in Reference (1)of the Related Art List, for reducing the power consumed by the mobileterminal device is applied to the power saving of thespeaker-microphone, the positional information cannot be acquired atplaces like indoor spaces or the shadow of a building where no radiowaves sent from satellites constituting the GPS cannot be received. Thismay possibly cause malfunction.

SUMMARY

The present invention has been made in view of the foregoing points. Apurpose thereof is to provide a portable radio device and a radiocommunication method capable of performing the power saving of aspeaker-microphone, independent of specific profiles, even in anout-of-service area and at places where the positional informationacquired using the GPS cannot be acquired.

In order to resolve the foregoing problems, a portable radio deviceaccording to one embodiment of the present invention includes: ashort-range communication unit that transmits and receives voice data toand from an external radio device, using short-range radiocommunication, the external radio device having a function oftransmitting and receiving the voice data; a radio communication unitthat receives a signal of a control channel wirelessly transmitted froma base station, during standby, and that wirelessly communicates betweenthe portable radio device and a partner station with the base stationserving as a relay station, during a call; and a control unit thatenables the short-range communication unit to transmit and receive thevoice data when the radio communication unit receives, from the basestation, a signal valid to the portable radio device.

Another embodiment of the present invention relates also to a portableradio device. The portable radio device includes: a short-rangecommunication unit that transmits and receives voice data to and from anexternal radio device, using short-range radio communication, theexternal radio device having a function of transmitting and receivingthe voice data; a radio communication unit that receives a signal of acontrol channel wirelessly transmitted from a base station, duringstandby, and that wirelessly communicates between the portable radiodevice and a partner station with the base station serving as a relaystation, during a call; a positional information acquiring unit thatacquires positional information on a present position of the portableradio device; a positional information determining unit that determinesby the radio communication unit, based on the positional information,whether or not the portable radio device is located within apredetermined area where the control channel is receivable; and acontrol unit that enables the short-range communication unit to transmitand receive the voice data when the radio communication unit receives,from the base station, a signal valid to the portable radio device orwhen it is determined by the positional information determining unitthat the portable radio device is located within the predetermined area.

Still another embodiment of the present invention relates to a radiocommunication method. The radio communication method includes having aportable radio device enable a function of transmitting and receivingvoice data to and from an external portable radio device, which isconnected by a short-range radio communication unit and which transmitsand receives voice data, when the portable radio device determines thata signal of a control channel transmitted from a base station, whichrelays communication between the portable radio devices, is a signalvalid to the portable radio device.

Still another embodiment of the present invention relates also to aradio communication method. The radio communication method includes:having a portable radio device enable a function of transmitting andreceiving voice data to and from an external portable radio device,which is connected by a short-range radio communication unit and whichtransmits and receives voice data, when the portable radio devicedetermines that a signal of a control channel transmitted from a basestation, which relays communication between the portable radio devices,is a signal valid to the portable radio device, or when the portableradio device determines that a result of measuring a position ofpositional information is in a range where the signal of the controlchannel transmitted from the base station is acquirable.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described by way of examples only, withreference to the accompanying drawings, which are meant to be exemplary,not limiting and wherein like elements are numbered alike in severalFigures in which:

FIG. 1 is a schematic system configuration showing an exemplary radiocommunication system to which a portable radio device and a radiocommunication method according to an embodiment of the present inventionare applied;

FIG. 2 is a block diagram showing a structure of the portable radiodevice of FIG. 1 according to an embodiment;

FIG. 3 is a block diagram showing a structure of a speaker-microphone ofFIG. 1;

FIG. 4 is a sequence diagram to explain operations of a portable radiodevice and a speaker-microphone according to an embodiment of thepresent invention;

FIG. 5A and FIG. 5B are flowcharts showing the respective operations ofmajor components of FIG. 4; and

FIG. 6 is a logic diagram showing an exemplary power save determiningcircuit.

DETAILED DESCRIPTION

The invention will now be described by reference to the preferredembodiments. This does not intend to limit the scope of the presentinvention, but to exemplify the invention.

A description is now given of one embodiment of the present inventionwith reference to Figures.

FIG. 1 is a schematic system configuration showing an exemplary radiocommunication system to which a portable radio device and a radiocommunication method according to an embodiment of the present inventionare applied. In FIG. 1, a radio communication system 100 is acommunication system in which portable radio devices 20-1, 20-2 and 20-3according to the present embodiment can mutually communicate with eachother with a base station 10 serving as a relay station. Here, theportable radio devices 20-1, 20-2 and 20-3 are located within a radiocommunication enabled area 1 of a base station 10. It is assumed hereinthat a simplex (half duplex) scheme is used in conducting a voice(audio) communication between the portable radio devices 20-1, 20-2 and20-3. Also, the portable radio devices 20-1, 20-2 and 20-3 are movable.

In FIG. 1, the portable radio device 20-1 is communicatable, viaBluetooth, with a battery-powered speaker-microphone 30, which is amovable external radio device. A portable radio device 20′ and aspeaker-microphone 30′ indicate how the portable radio device 20-1 ismoved, together with the speaker-microphone 30, to an area outside theradio communication enabled area 1 (namely, a radio communicationunreachable area in FIG. 1). Furthermore, as shown in FI. 1, theportable radio devices 20-1, 20-2 and 20-3 each has a function ofreceiving GPS signals relayed by a satellite or satellites (hereinafterreferred to as a GPS satellite or GPS satellites) 5 thatconstitutes/constitute a part of GPS, no matter whether each of theportable radio devices 20-1, 20-2 and 20-3 is located within or outsidethe radio communication enabled area 1.

The radio communication system 100 is a wireless communication systemusing a trunking method. In the trunking method, the portable radiodevices 20-1, 20-2 and 20-3 are each constantly receiving a controlchannel (ch) from the base station 10 during standby (waiting time).

In the radio communication system 100 using the trunking method, eachportable radio device places a call by using a control ch via the basestation 10, then moves to a voice channel (ch) not used by both theportable radio device and a partner radio device, and performs verbal(voice) communication. After having moved to the voice ch, any one ofthe portable radio devices 20-1, 20-2 and 20-3 transmits a message andthen another user (a plurality of users possible) receives the message,when a single message transmission is used. Thus, even while the twoportable radio devices 20-1 and 20-2 alternately converse with eachother with the base station 10 used as the relay station in a group ofthe portable radio devices 20-1, 20-2 and 20-3 located within the radiocommunication enabled area 1, the third portable radio device 20-3 canintercept the conversation taking place between the portable radiodevices 20-1 and 20-2.

In this case, even though the portable radio device 20-1 stops thetransmission while the portable radio device 20-2 is still transmittingmessages, the transmission from the base station 10 continues. Thus, thereceived signals continue to arrive without interruption. If continuesthe state where no one transmits messages, the base station 10 stopsrelaying the messages. As no signals of the voice ch is sent from thebase station 10, the portable radio devices 20-1, 20-2 and 20-3 eachsearches for a control ch and then receives the control ch.

A description is now given of a structure of a portable radio deviceaccording to an embodiment of the present invention. FIG. 2 is a blockdiagram showing a structure of the portable radio device according to anembodiment of the present invention. Since the portable radio devices20-1, 20-2 and 20-3 have the same structure, they are hereinaftergenerically referred to as “portable radio device 20” or “portable radiodevices 20”, and a description thereof will be given as that of“portable radio device 20” or “portable radio devices 20”.

As shown in the block diagram of FIG. 2, the portable radio device 20 isconfigured such that a microcomputer 21 can carry out two-waycommunication with a Bluetooth circuit 22 and a baseband processing unit25. Also, the microcomputer 21 receives GPS data, fed from a GPS circuit23, and transmission control signals, sent from a PTT circuit 26, andthen supplies display data to a display unit 27 so as to control theportable radio device in a unified manner. Also, the microcomputer 21operates by receiving the electric power from a battery 28 in the sameas the Bluetooth circuit 22, the GPS circuit 23, a radio circuit 24, thebaseband processing unit 25, the PTT circuit 26 and the display unit 27operate thereby.

The Bluetooth circuit 22 constitutes a short-range communication unit inan embodiment of the present invention. Also, the Bluetooth circuit 22,which is used to communicate via Bluetooth with the speaker-microphone30, receives speaker-microphone communication data sent from thespeaker-microphone 30 and then supplies the received speaker-microphonecommunication data to the microcomputer 21. Data to be transmitted fromthe portable radio device 20 to the speaker-microphone 30 is supplied tothe Bluetooth circuit 22 from the microcomputer 21. Then, the data isconverted into a predetermined signal form for use in Bluetoothcommunication, and the converted data is transmitted to thespeaker-microphone 30.

The GPS circuit 23 constitutes a positional information acquiring unitin the present disclosure. The GPS circuit 23 receives GPS signals sentfrom the GPS satellites 5, then converts the GPS signals into GPS data,and supplies the GPS data to the microcomputer 21. Based on the GPS datasupplied from the GPS circuit 23, the microcomputer 21 conducts a knownanalysis algorithm for determining the positional information tocalculate the present position (the latitude and longitude) of theportable radio device 20. Further, the microcomputer 21 references atable for a radio communicatable area in which the present positionthereof is registered and then determines whether or not the portableradio device 20 is located within the radio communication enabled area1. The radio circuit 24 receives radio signals of the control chwirelessly transmitted directly from the base station 10 or voicesignals wirelessly transmitted over the voice ch from a partner stationwith the base station 10 used as the relay station. The radio signals orvoice signals received are then converted into wireless voice data of apredetermined intermediate frequency, for example, and the wirelessvoice data is supplied to the baseband processing unit 25.

The baseband processing unit 25, together with the radio circuit 24,constitutes a radio communication unit in the present disclosure. Thebaseband processing unit 25 converts the wireless voice data suppliedinto a baseband signal and processes this baseband signal by using aknown processing, and then supplies the thus processed signal to themicrocomputer 21. If an input signal supplied from the basebandprocessing unit 25 is a display signal, the microcomputer 21 convertsthe input signal into display data and supplies the display data to thedisplay unit 27 so as to have the display data displayed thereby. If theinput signal supplied therefrom is voice data, the microcomputer 21supplies the voice data to the Bluetooth circuit 22, where the voicedata is converted into a predetermined signal form suitable for theBluetooth communications, and the signal thus converted by the Bluetoothcircuit 22 is transmitted to the speaker-microphone 30 so as to producevoice sound through a speaker portion.

The microcomputer 21 acquires a received field strength (received signalstrength indication (RSSI) data) from the input signal supplied from thebaseband processing unit 25. When the transmission control signal is fedfrom the PTT circuit 26 upon activation of the PTT switch, transmittingvoice data, which has been collected by a microphone portion of thespeaker-microphone 30 and then transmitted via Bluetooth communications,is fed through the Bluetooth circuit 22, and the microcomputer 21further wirelessly transmits the transmission voice data to the partnerstation through the baseband processing unit 25 and the radio circuit24. The display unit 27 displays a control condition of thespeaker-microphone 30. The microcomputer 21 constitutes an arithmeticoperator (calculator), a disconnection request transmitting unit and apositional position determining unit of the present disclosure.

A description is now given of the speaker-microphone. FIG. 3 is a blockdiagram showing a structure of the speaker-microphone according to anembodiment. In FIG. 3, the speaker-microphone 30 includes amicrocomputer 31, a Bluetooth circuit 32, an audio circuit 33, a PTTcircuit 34, and a display unit 35. The speaker-microphone 30 isconfigured such that these components thereof operate by receiving theelectric power from a battery 36. Though omitted in FIG. 3, thespeaker-microphone 30 further includes a speaker portion and amicrophone portion.

The Bluetooth circuit 32 communicates via Bluetooth with the portableradio device 20. The Bluetooth circuit 32 receives signals (e.g., thereceived voice and various requests) transmitted from the portable radiodevice 20 and supplies them to the microcomputer 31, and transmitstransmitting voice signals fed from the microcomputer 31 to the portableradio device 20.

When the signal fed from the Bluetooth circuit 32 is the received voicedata, the microcomputer 31 has the audio circuit 33 convert the signalinto a received voice of analog signal and has the speaker portionproduce the analog signal as voice sound. When the signals fed from theBluetooth circuit 32 are various requests, the microcomputer 31 carriesout predetermined processings according to the requests. When thetransmission control signal is fed from the PTT circuit 26 uponactivation of the PTT switch, voice data of digital signal obtained,when the transmitting voice data collected by the microphone portion ofthe speaker-microphone is converted by the audio circuit 33, is suppliedto the microcomputer 31. The microcomputer 31 then transmits this voicedata to the Bluetooth circuit 32 and has the Bluetooth circuit 32transmit the voice data to the portable radio device 20. Also, themicrocomputer 21 supplies display data to the display unit 35 and hasthe display unit 35 display the display data. The display unit 35displays a control condition of the speaker-microphone and the like.

A detailed description is now given of the portable radio deviceaccording to an embodiment.

FIG. 4 is a sequence diagram to explain operations of a portable radiodevice and a speaker-microphone according to an embodiment of thepresent invention. FIG. 2 mainly shows operations of the microcomputer21 and the Bluetooth circuit 22 in the portable radio device 20 of FIG.2 and operations of the Bluetooth circuit 32 and the microcomputer 31 inthe speaker-microphone 30 of FIG. 3.

A description is first given of an operation during standby (waitingtime) or during a standby state (mode). As discussed earlier, duringstandby, the portable radio device 20 receives a standby signal, whichis constantly transmitted from the base station 10 over the control ch,and supplies the standby signal to the microcomputer 21 via the radiocircuit 24 and the baseband processing unit 25. As a result, duringstandby, the microcomputer 21 of the portable radio device 20 monitorsthe RSSI level (received signal strength) of the receiving-standbysignal and the positional information based on the GPS data (Step Sa1).If it is detected, based on the RSSI level (received signal strength) ofthe standby signal and the positional information based on the GPS data,that the portable radio device 20 has entered an area outside the radiocommunication enabled area 1 of the base station (see FIG. 1) (i.e., anout-of-service area), the microcomputer 21 carries out a power saveprocessing of the speaker-microphone (Step Sa2).

In conjunction with FIG. 5A, a detailed description is further given ofthe processing at Steps Sa1 and Sa2 during standby. First, in a standbystate, the microcomputer 21 monitors whether or not the RSSI level(received signal strength) of the receiving-standby signal is less thanor equal to a threshold value (Step S21, which corresponds to Step Sa1of FIG. 4). If the RSSI level thereof is less than or equal to thethreshold value, the microcomputer 21 continues to determine whether aGPS function is active or not (Step S22). That is, at Step S22, themicrocomputer 21 determines that the GPS function is active (valid),when the user operates on the GPS function of the portable radio device;the microcomputer 21 determines that the GPS function is not active(invalid), when he/she does not use the GPS function thereof.

When it is determined, at Step S22, that the GPS function is invalid,the RSSI level (received signal strength) of the receiving-standbysignal is determined to be less than or equal to the threshold value).With this determination result, the control ch is not received and it istherefore determined that the portable radio device is located in theout-of-service area. Hence, the microcomputer 21 carries out the powersave processing of the speaker-microphone 30 (Step S24, whichcorresponds to Step Sa2 of FIG. 4).

When, on the other hand, it is determined, at Step S22, that the GPSfunction is valid, the microcomputer 21 references, for example, theregistration table of the radio communication enabled area by using thepositional information calculated based on the GPS data, and thendetermines whether or not the calculated positional informationindicates that the portable radio device is located within the radiocommunication enabled area (namely, within a service area (call possiblezone) or not) (Step S23). If the positional information indicating theservice area can be acquired, the processing step is returned to StepS21 and then resumed is monitoring whether or not the RSSI level(received signal strength) of the standby signal is less than or equalto the threshold value. In this case, the portable radio device 20cannot receive the control ch because the portable radio device 20 is inthe shadow of a building, for example. However, it is determined, fromthe GPS data, that the portable radio device is located within the radiocommunication enabled area 1 and that the control ch can be receivedagain, and therefore the processing at Step S21 continues.

When, on the other hand, at Step 23 the microcomputer 21 determines thatthe calculated positional information indicates an area outside theradio communication enabled area (i.e., an out-of-service area), thepower save processing of the speaker-microphone 30 is carried out (StepS24, which corresponds to Step Sa2 of FIG. 4). That is, when it isdetermined, at Step S22, that the GPS function is valid and both whenthe RSSI level (received signal strength) of the receiving-standbysignal is less than or equal to the threshold value and when thepositional information indicates an out-of-service area, themicrocomputer 21 carries out the power save processing of thespeaker-microphone 30. This is because, in this case, the portable radiodevice 20 is in a state where the transmission and receiving function islost, and therefore the electric power will be wasted if a transmissiontrigger (transmitter button, etc.) and the speaker-microphone 30 forcontrolling the telephone calling are still in an operable (standby)state then.

Now, refer back to FIG. 4 to continue the explanation. If the power saveprocessing is to be carried out (Step Sa2), the microcomputer 21 outputsa disconnection request. Subsequent to a standby operation (Step Sb1) sofar, the Bluetooth circuit 22 transmits the disconnection request, sentfrom the microcomputer 21, to the speaker-microphone 30 (Step Sb2). Whenthe Bluetooth circuit 32 of the speaker-microphone 30 receives theaforementioned disconnection request during the previous standbyoperation (Step Sc1), the Bluetooth circuit 32 instructs themicrocomputer 31 to switch the on-going standby operation (Step Sd1) tothe execution of the power save processing (Step Sd2), by an interruptprocessing. This allows the speaker-microphone 30 to start a power savemode where the feeding of electricity from the battery 36 to thespeaker-microphone 30 is cut (Step Sd3).

During a power save period of the speaker-microphone 30, the Bluetoothcircuits 22 and 32 are each in a state of waiting for a connectionrequest (Steps Sbs and Sc3). The microcomputer 21 of the portable radiodevice 20 now monitors whether or not the portable radio device 20 hasentered the radio communication enabled area 1 of the base station (seeFIG. 1) (i.e., the service area), based on the positional informationcalculated from the RSSI level (received signal strength) of the standbysignal and the GPS data (Step Sa3). When it is detected that theportable radio device 20 is located within the service area, themicrocomputer 21 carries out a power restoration processing of thespeaker-microphone 30 (Step Sa4) and outputs the connection request.

In conjunction with FIG. 5B, a detailed description is further given ofthe processing at Steps Sa3 and Sa4 during standby. First, in a standbystate of the portable radio device 20, the microcomputer 21 monitorswhether or not the RSSI level (received signal strength) of thereceiving-standby signal is greater than or equal to the threshold value(Step S41). If the RSSI level thereof is greater than or equal to thethreshold value, the power restoration processing of thespeaker-microphone 30 is carried out (Step S44, which corresponds toStep Sa4 of FIG. 4).

Now, refer back to FIG. 4 to continue the explanation. If the powerrestoration processing is to be carried out (Step Sa4), themicrocomputer 21 outputs a connection request. Subsequent to a powersave operation (Step Sb3) so far, the Bluetooth circuit 22 transmits theconnection request, sent from the microcomputer 21, to thespeaker-microphone 30 (Step Sb4). When, subsequent to the power saveoperation (Step Sc3) so far, the Bluetooth circuit 32 of thespeaker-microphone 30 receives the aforementioned connection request(Step Sc4), the Bluetooth circuit 32 instructs the microcomputer 31 toswitch the power save operation (Step Sd3) to the execution of the powerrestoration processing (Step Sd4) by an interrupt processing.

As result, the electric power restarts to be supplied to thespeaker-microphone 30 from the battery 36, and the speaker-microphone 30is set to a standby state (Step Sd5). Also, the Bluetooth circuits 22and 32 are each set to a standby state (Step Sb5 and Step Sc5), and themicrocomputer 21 monitors again the positional information based on theRSSI level (received signal strength) of the receiving-standby signaland the GPS data.

Thus, during standby, the portable radio device 20 according to thepresent embodiment maintains the wireless connection status with thespeaker-microphone 30, as long as the positional information based onthe GPS data indicates that the portable radio device 20 is locatedwithin the service area, even though the RSSI level of the standbysignal of the control ch is less than or equal to the threshold valuebecause of the portable radio device being in the shadow of a building,for example, and it is therefore determined that the receiving-standbysignal cannot be received. Also, if, at Step S41, the RSSI level of thestandby signal of the control ch is greater than or equal to thethreshold value and it is determined that the control ch can bereceived, the wireless connection status with the speaker-microphone 30is maintained. This is because it is determined that the transmissionand the receiving are still possible considering (1) a case where theGPS signals cannot be received due to the reason why the portable radiodevice 20 may be located inside a building or (2) a case where thestandby signal can be received through reflection and the like eventhough the portable radio device 20 is located in an out-of-servicearea.

The description has been given of a procedure for determining whetherthe portal radio device 20 is in the service area or not, by the RSSIlevel of the standby signal. However, this should not be considered aslimiting. For example, whether or not the portable radio device 20 is inthe service area may be determined based on whether or not a signalvalid to the portable radio device is received. More specifically,whether or not it is in the service area may be determined based onwhether or not there is a signal synchronous with the standby signal.Or, for example, whether or not it is in the service area may bedetermined based on whether or not the bit error ratio (BER) of thestandby signals is less than or equal to a threshold value.

A description is next given of an operation during receiving or during areceiving state (mode).

As explained in the radio system employing the trunking method, “duringreceiving” or “during a receiving state (mode)” is a state where a callplaced over the control ch is received from the partner station 20 in astandby state over the control ch and then the voice signal from thepartner station is being received after the communication channel hasmoved to the voice ch. Thus, no power save processing of thespeaker-microphone 30 is carried out during receiving.

If, in the trunking method, the signals of the voice ch cease to arrivefor a predetermined length of time, the channel is returned to thecontrol ch and the operation mode is set to a standby state.

The Bluetooth circuit 22 transmits the received voice data to thespeaker-microphone 30. The Bluetooth circuit 32 of thespeaker-microphone 30 receives the voice data sent from the portableradio device 20 and then supplies the received voice data to themicrocomputer 31. The microcomputer 31 has the speaker portion sound outthe input voice data, through the audio circuit 33, as the receivedvoice.

A description is next given of an operation during transmission orduring a transmission state (mode).

In the trunking method, the portable radio device 20 will not be in atransmission state unless either the control ch or the voice ch isreceived. Thus it is presupposed in the trunking method that thespeaker-microphone 30 is not in a power save state. Similar to theprocessing carried out during receiving, no power save processing of thespeaker-microphone 30 is carried out during transmission, too.

If the portable radio device 20 terminates the transmission and then apredetermined length of time has passed without receiving any voice callresponse from the partner station, the base station 10 terminates arelay processing. When the signals no longer exist in the voice ch, thecommunication channel returns to the control ch, and the portable radiodevice 20 is in a standby state.

The transmitting voice is collected by the microphone portion of thespeaker-microphone 30 and is fed to the microcomputer 31 through theaudio circuit 33 as the transmitting voice data. The microcomputer 31supplies this transmitting voice to the Bluetooth circuit 32 so as to betransmitted to the portable radio device 20. The Bluetooth circuit 22receives the transmitting voice data, transmitted from the Bluetoothcircuit 32, and supplies it to the microcomputer 21. While the PTTswitch of the portable radio device 20 is pressed down, themicrocomputer 21 converts the transmitting voice data, fed from theBluetooth circuit 22, into a predetermined signal form through thebaseband processing unit 25 and the radio circuit 24.

Subsequent to this, all of the following processings are carried outduring a transmission period. That is, during the transmission period,the voice is inputted to the microcomputer 31, the transmitting voicedata is transmitted from the Bluetooth circuit 32, the transmittingvoice data is received by the Bluetooth circuit 22, and themicrocomputer 21 outputs the thus inputted transmitting voice data tothe baseband processing unit 25. As the transmission of voice isterminated after this, the microcomputer 31, the Bluetooth circuit 32and the Bluetooth circuit 22 are all in their standby states. Then, thePTT switch of the portable radio device 20 is no longer pressed down andthe portable radio device 20 is switched to the receiving mode.

Determining when to invoke the power save processing of thespeaker-microphone 30 by the microcomputer 31 can be done sofwarewise.However, this is should not be considered as limiting and, for example,this may be configured by a logic circuit as shown in FIG. 6. FIG. 6 isa circuit diagram showing an exemplary power save determining circuit.In FIG. 6, a power save determining circuit 40 is configured by atwo-input AND circuit 41 and two-input OR circuits 42 and 43. Thetwo-input AND circuit 41 outputs an AND signal indicating a logicalproduct (AND) of a determination signal and a GPS function determinationsignal. Here, the determination signal is either an “H” level signal oran “L” level signal wherein the determination signal is at “H” levelwhen the positional information calculated by the microcomputer 21 fromthe GPS data indicates a service area, and the determination signal isat “L” level when it indicates an out-of-service area. Similarly, theGPS function determination signal is either an “H” level signal or an“L” level signal wherein the GPS function determination signal is at “H”level when the GPS function is turned on (enabled), and the GPS functiondetermination signal is at “L” level when the GPS function is turned off(disabled).

The two-input OR circuit 42 outputs an OR signal indicating a logicalsum (OR) of a signal, which is inputted to one of input terminals of thetwo-input OR circuit 42, and an output signal of the AND circuit 41,which is inputted to the other thereof. An RSSI determination signal isinputted to one of the input terminals of the two-input OR circuit 42.Here, the RSSI determination signal is at “H” level when the RSSI of thereceiving-standby signal of the control ch is greater than or equal tothe threshold value, and the RSSI determination signal is at “L” levelwhen it is less than or equal to the threshold value.

The two-input OR circuit 43 outputs an OR signal indicating a logicalsum (OR) of a mode determination signal, which is inputted to one ofinput terminals of the two-input OR circuit 43, and an output signal ofthe OR circuit 43, which is inputted to the other thereof. This ORsignal is outputted as a power save mode signal from the two-input ORcircuit 43. Here, the mode determination signal goes “H” when theportable radio device 20 is in a transmission state, and the modedetermination signal goes “L” when it is in a standby state or areceiving state. The power save mode signal indicates a power save modewhen it is at “L” level, and the power save mode signal indicates anormal operation when it is at “H” level. Thus, where the portable radiodevice 20 is in a standby state, the OR circuit 43 outputs a signalindicative of a power save mode when the GPS function is turned off andwhen the RSSI of the receiving-standby signal is less than or equal tothe threshold value. Also, where the portable radio device 20 is in astandby state, the OR circuit 43 outputs a signal indicative of a powersave mode when the GPS function is turned on and when the positionalinformation based on the GPS data indicates an out-of-service area inaddition to the above condition.

As described above, by employing the portable radio device 20 accordingto the present embodiment, the information as to whether or not theportable radio device 20 is located within the radio communicationenabled area 1 is accurately obtained based on the information, such asthe RSSI level (received signal strength) of the receiving-standbysignal, acquired by receiving the signals from the base station 10 andthe positional information acquired from the received GPS data. If,during standby, the portable radio device 20 is located outside theradio communication enabled area 1, the power save mode is carried outwhere the feeding of electricity from the battery to thespeaker-microphone for receiving and transmitting the voice signals viaBluetooth communications is cut. Also, when it is determined, based onat least one of the above two sets of information, that the portableradio device, which is controlled under the power save mode, has enteredthe radio communication enabled area 1, the operation mode is returnedto a power mode where the speaker-microphone is powered by the battery.

Thus, by employing the portable radio device 20 according to the presentembodiment, the power saving can be achieved independent of theBluetooth profiles and without the need of issuing a power savingcommand using a serial communication profile or without the need ofusing the hands-free profile. Also, the commands used in the powersaving and the power restoration according to the present embodiment area disconnection request and a connection request only. Thus, the triggersuch as a voice transmission request is no longer required, so that thepower saving can be automatically carried out by his/her own terminaldevice only.

Moreover, according to the present embodiment, two or more sets ofinformation, including the information, such as the RSSI level (receivedsignal strength) of the receiving-standby signal, acquired by receivingthe signals sent from the base station 10 and the positional informationacquired from the received GPS data, are used simultaneously. Thisresolves the problem concerning the accuracy in the determination of theposition of the portable radio device located indoors or in the shadowof a building, when only the GPS signals are used while the device is inthe power saving mode, so that the malfunction can be prevented.

The present invention has been described based upon illustrativeembodiments. These exemplary embodiments are intended to be illustrativeonly and not limiting. For example, a short-range radio communicationscheme, such as WiFi, other than the Bluetooth may also be used for thecommunications between the portable radio device and thespeaker-microphone.

What is claimed is:
 1. A portable radio device comprising: a short-rangecommunication unit that transmits and receives voice data to and from anexternal radio device, using short-range radio communication, theexternal radio device having a function of transmitting and receivingthe voice data; a radio communication unit that receives a signal of acontrol channel wirelessly transmitted from a base station, duringstandby, and that wirelessly communicates using a half duplex schemebetween the portable radio device and a partner station with the basestation serving as a relay station, during a call; a positionalinformation acquiring unit that acquires positional information on apresent position of the portable radio device; a positional informationdetermining unit that determines, based on the positional information,whether or not the portable radio device is located within an area wherereception of the control channel by the radio communication unit isenabled; and a control unit that disables a function, of transmittingand receiving the voice data, in the short-range communication unit,when a signal strength of the signal of the control channel received bythe radio communication unit is less than or equal to a predeterminedvalue and when it is determined by the positional informationdetermining unit that the portable radio device is not located withinthe predetermined area.
 2. A radio communication method including havinga portable radio device for half duplex wireless communication disable afunction of transmitting and receiving voice data to and from anexternal portable radio device, which is connected to the portable radiodevice by a short-range radio communication unit and which transmits andreceives voice data, when a signal strength of the signal of the controlchannel transmitted from a base station, which relays communicationbetween the portable radio device and a partner station, is less than orequal to a predetermined value and when the portable radio devicedetermines that a result of measuring a position of positionalinformation is not in a range where the signal of the control channeltransmitted from the base station is acquirable.